sb_write
struct closure sb_write;
struct closure sb_write;
closure_put(&dc->sb_write);
closure_type(dc, struct cached_dev, sb_write);
struct closure *cl = &dc->sb_write;
closure_put(&ca->set->sb_write);
closure_type(c, struct cache_set, sb_write);
struct closure *cl = &c->sb_write;
sb_write(cache_dev, &sb);